Compare two date in ember

I Want to put validation of end date should be max or equal from effective date if end date is there

effectiveDate: validator('presence', {
presence: true,
message: 'Please enter a valid value'
}), 

endDate: validator('format', {
value(model, attribute) {
// Validate a value that is not the current attribute
 alert(this.get('model').get('effectiveDate'));

 return null;
 },